The purpose of this non-experimental, correlational, explanatory, cross-sectional design with quantitative methods was to examine the relationship between the length of the school day and the percentage of students who achieved Met Expectations and Exceeded Expectations scores on the 2018 Partnership for Assessment of Readiness for College and Careers (PARCC ) for Algebra II. The study was conducted to explain the influence the length of school day had on Algebra II students who took PARCC in 2018. Additionally, this study examined the influence of staff, student, and school variables such as staff attendance, staff mobility, and percentage of staff with master's degrees or higher, student attendance, the percentage of students on free and reduced lunch, limited English proficiency, the percentage of students with disabilities, and school size. The variable of interest, the length of the school day, was found not to be a statistically significant predictor of achievement on the 2018 PARCC for Algebra II. Of the eight variables included within this study, the percentage of students on free and reduced lunch, limited English proficiency, the percentage of students with disabilities, and the percentage of staff with master's degree or higher were found to be statistically significant predictors of student achievement. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com.bibliotheek.ehb.be/en-US/products/dissertations/individuals.shtml.]